The once-daily drug is already approved in the country for this subset of patients as second-line use, but the new first-line setting will see the drug reach more patients earlier on in their treatment regimen.

Following a priority review, the Japanese Ministry of Health, Labour and Welfare based the approval on data from the phase III FLAURA trial, which included Japanese patients.

That trial demonstrated Tagrisso’s safety, which was in line with those observed in prior clinical trials.

The drug was also reviewed against other first-line EGFR tyrosine kinase inhibitors – Roche’s Tarceva and AZ’s and Teva’s Iressa – in previously untreated patients with locally-advanced or metastatic EGFR-mutated NSCLC.

Dave Fredrickson, Executive Vice President, Head of the Oncology Business Unit, AstraZeneca, said: “Tagrisso is already approved in Japan for the treatment of patients with EGFR T790M mutation-positive inoperable or recurrent NSCLC that is resistant to existing first-line EGFR-inhibitor medicines.

“Today’s approval moves the use of Tagrisso to the first-line setting, replacing older medicines which, given the high prevalence of the EGFR mutation in Japan, offers an important new treatment option for these patients.”

According to the company, up to 40% of lung cancer patients in Asia have EGFRm NSCLC, and these patients are particularly sensitive to treatment with EGFR-TKIs, which block the cell-signalling pathways that drive the growth of tumour cells.

Approximately 25% of these patients have brain metastases at diagnosis, which often reduces median survival to less than 8 months.

Tapping into this market is also important for AstraZeneca, with the company predicting that Tagrisso could generate annual sales of up to $4bn.

The drug is now approved in 40 countries for this indication, and more than 75 countries – including the US and Europe – for second-line use.